JdbcUtil

转自：https://github.com/ghyg525/util_java_jdbc

JdbcUtil.java

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;/*** 简单封装数据库工具类* 查询返回结果有数组, List, Map* 其他类型语句都调用execute* @author YJ*/
public class JdbcUtil {/*** 查询返回String二维数组* @param sql* @param args* @return*/public static String[][] queryForArray(String sql, Object... args) {Connection conn = null;PreparedStatement stmt = null;ResultSet rs = null;String[][] result = null;try {conn = getConnection();stmt = conn.prepareStatement(sql,ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);if (args != null) {for (int i = 0; i < args.length; i++) {stmt.setObject(i + 1, args[i]);}}rs = stmt.executeQuery();rs.last();int rows = rs.getRow();rs.beforeFirst();ResultSetMetaData rsmd = rs.getMetaData();int cols = rsmd.getColumnCount();result = new String[rows+1][cols];for (int i = 0; i < cols; i++) {result[0][i] = rsmd.getColumnName(i + 1);}int currentRow = 1;while (rs.next()) {for (int i = 0; i < cols; i++) {result[currentRow][i] = rs.getObject(i + 1).toString();}currentRow++;}} catch (SQLException e) {e.printStackTrace();} finally {try {if (rs != null)rs.close();if (stmt != null)stmt.close();if (conn != null)conn.close();} catch (SQLException e) {e.printStackTrace();}}return result;}/*** 查询返回List类型* @param sql* @param args* @return 多条记录的List集合*/public static List<Map<String, Object>> queryForList(String sql, Object... args) {Connection conn = null;PreparedStatement stmt = null;ResultSet rs = null;List<Map<String, Object>> result = new ArrayList<Map<String, Object>>();try {conn = getConnection();stmt = conn.prepareStatement(sql);if (args != null) {for (int i = 0; i < args.length; i++) {stmt.setObject(i + 1, args[i]);}}rs = stmt.executeQuery();ResultSetMetaData rsmd = rs.getMetaData();int cols = rsmd.getColumnCount();String[] colNames = new String[cols];for (int i = 0; i < cols; i++) {colNames[i] = rsmd.getColumnName(i + 1);}while (rs.next()) {Map<String, Object> row = new LinkedHashMap<String, Object>();for (int i = 0; i < cols; i++) {row.put(colNames[i], rs.getObject(i + 1));}result.add(row);}} catch (SQLException e) {e.printStackTrace();} finally {try {if (rs != null)rs.close();if (stmt != null)stmt.close();if (conn != null)conn.close();} catch (SQLException e) {e.printStackTrace();}}return result;}/*** 查询返回Map类型 当确定返回结果唯一时调用* @param sql* @param args* @return 一条记录的Map*/public static Map<String, Object> queryForMap(String sql, Object... args) {List<Map<String, Object>> result = queryForList(sql, args);Map<String, Object> row = null;if (result.size() == 1) {row = result.get(0);return row;} else {return null;}}/*** 执行除查询外(增加/删除/修改)* @param sql* @param args* @return 是否执行成功*/public static boolean execute(String sql, Object... args) {Connection conn = null;PreparedStatement stmt = null;boolean result = true;try {conn = getConnection();stmt = conn.prepareStatement(sql);if (args != null) {for (int i = 0; i < args.length; i++) {stmt.setObject(i + 1, args[i]);}}stmt.executeUpdate();} catch (SQLException e) {e.printStackTrace();result = false;} finally {try {if (stmt != null)stmt.close();if (conn != null)conn.close();} catch (SQLException e) {e.printStackTrace();}}return result;}/*** 获得数据库连接* @return*/private static Connection getConnection() {Connection conn = null;try {Class.forName(getProperties().getProperty("driver"));conn = DriverManager.getConnection(getProperties().getProperty("url"),getProperties().getProperty("username"), getProperties().getProperty("password"));} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}return conn;}/*** 读取配置文件信息* @return*/private static Properties getProperties(){Properties properties = new Properties();try {properties.load(JdbcUtil.class.getResourceAsStream("/jdbc.properties"));} catch (IOException e) {e.printStackTrace();}return properties;}}

jdbc.properties

url=jdbc:mysql://localhost:3306/esweb
driver=com.mysql.jdbc.Driver
username=root
password=root

测试：

public class JdbcMysql {public static void main(String[] args) {String sql1 = "select * from screen_201808";String sql2 = "select * from screen_201808 where id = ?";System.out.println(JdbcUtil.queryForArray(sql1)[1][1]);System.out.println(JdbcUtil.queryForList(sql1));System.out.println(JdbcUtil.queryForMap(sql2,1));}
}